Microalgae are photosynthetic cyanobacteria and eukaryotic microorganisms, mainly living in the water. In agriculture, numerous studies have been conducted to utilize microalgae as a biostimulant resource. Scenedesmus has been known to be one such microalga that can promote plant growth by secretion of auxin or cytokinin hormone analogs. However, no research has been performed on the effect of microalgae treatment on plant microbiota communities. This study was conducted to investigate the mode of action of microalgae as biostimulants in a plant microbiota perspective by using Scenedesmus sp. CHK0059 (also known as species Chlorella fusca ), which has been well documented as a biostimulant for strawberries. The strawberry cultivar Keumsil was bred with Seolhyang and Maehyang as the parent cultivars. Using these three cultivars, microbiota communities were evaluated for changes in structural composition according to the CHK0059 treatment. CHK0059-treated Seolhyang, and CHK0059-untreated Maehyang were similar in microbial diversity in the endosphere. From a microbiota community perspective, the diversity change showed that CHK0059 was affected by the characteristics of the host. Conversely, when CHK0059 treatment was applied, populations of Streptomyces and Actinospica were observed in the crown endosphere.

Plant growth-promoting rhizobacteria (PGPR) affect plant growth via various direct or indirect mechanisms. These microorganisms are the potential tools for sustainable agriculture. In this study, eight different Pseudomonas strains (PM1 -PM8) isolated from rhizospheric soil were characterized plant growth-promoting characteristics, including indole-3-acetic acid (IAA) and Gibberellin (GA3) production, phosphate solubilization, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity and effects of direct inoculation on plant growth parameters (fresh weight, shoot length). All of these strains have their ability for solubilization of insoluble phosphate depending on pH decrease at the range around pH4 -5 at 2 days after inoculation. PM1, PM4, PM5 and PM7 species was capable of IAA production and PM4, PM5, PM7 and PM8 species have high activity for production of gibberellin (GA3) hormone. For ACC deaminase activity, PM1, PM3 and PM8 show high activity. Furthermore, all these species have significantly promoted the growth of the lettuce seedling plants for fresh weight and shoot length enhancement, so that these Pseudomonas species could be used as potential bio-fertilizer agents.

In the article titled Effect of Scenedesmus sp. CHK0059 on Strawberry Microbiota Community, the funding acknowledgment was partially incorrect as published.

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